Kinetics of heterogeneous reactions of HO2 radical at ambient concentration levels with (NH4)2SO4 and NaCl aerosol particles.
Kinetics of heterogeneous reactions of HO2 radical at ambient concentration levels with (NH4)2SO4 and NaCl aerosol particles.
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DOI：
10.1021/jp0769936
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发表时间：
2008-02
期刊：
影响因子：
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通讯作者：
F. Taketani;Y. Kanaya;H. Akimoto
中科院分区：
文献类型：
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作者：
F. Taketani;Y. Kanaya;H. Akimoto
利用气溶胶流动管(AFT)和化学转化/激光诱导荧光(CC/LIF)相结合的技术，测量了常温(760Torr和296+/-2K)下无机亚微米湿和干气溶胶颗粒((NH4)2SO4和NaCl2)的HO2吸收系数(γ)。CC/LIF技术使实验能够在与大气中几乎相同的HO2自由基浓度下进行。通过可垂直移动的PYREX管将HO2自由基注入AFT。测量了LIF强度随喷嘴位置的变化曲线，作为气溶胶浓度的函数。在相对湿度(RH)为20%和45%时，(NH4)2SO4干气溶胶的伽马值分别为0.04+/-0.02和0.05+/-0.02，而在相对湿度为20%和53%时，氯化钠干气溶胶的伽马值分别为<；0.01和0.02+/-0.01。对于湿(NH4)2SO4气溶胶，相对湿度为45%、55%、65%和75%时，测得的伽马值分别为0.11+/-0.03、0.15+/-0.03、0.17+/-0.04和0.19+/-0.04；对于湿(NH4)2SO4气溶胶，测得的伽马值分别为0.11+/-0.03、0.09+/-0.02和0.10+/-0.02。湿(NH4)2SO4和掺杂CuSO4的氯化钠气溶胶的伽马值分别为0.53+/-0.12和0.65+/-0.17。这些结果表明，气溶胶颗粒的组成、相对湿度和物相对HO2的吸收有重要影响。讨论了潜在的HO2损失过程及其对大气的贡献。
The HO2 uptake coefficient (gamma) for inorganic submicrometer wet and dry aerosol particles ((NH4)2SO4 and NaCl) under ambient conditions (760 Torr and 296 +/- 2 K) was measured using an aerosol flow tube (AFT) coupled with a chemical conversion/laser-induced fluorescence (CC/LIF) technique. The CC/LIF technique enabled experiments to be performed at almost the same HO2 radical concentration as that in the atmosphere. HO2 radicals were injected into the AFT through a vertically movable Pyrex tube. Injector position-dependent profiles of LIF intensity were measured as a function of aerosol concentration. Measured gamma values for dry aerosols of (NH4)2SO4 were 0.04 +/- 0.02 and 0.05 +/- 0.02 at 20% and 45% relative humidity (RH), respectively, while those of NaCl were <0.01 and 0.02 +/- 0.01 at 20% and 53% RH, respectively. For wet (NH4)2SO4 aerosols, measured gamma values were 0.11 +/- 0.03, 0.15 +/- 0.03, 0.17 +/- 0.04, and 0.19 +/- 0.04, at 45%, 55%, 65%, and 75% RH, respectively, whereas for wet NaCl aerosols the values were 0.11 +/- 0.03, 0.09 +/- 0.02, and 0.10 +/- 0.02 for 53%, 63%, and 75% RH, respectively. Wet (NH4)2SO4 and NaCl aerosols doped with CuSO4 showed gamma values of 0.53 +/- 0.12 and 0.65 +/- 0.17, respectively. These results suggest that compositions, RH, and phase for aerosol particles are significant to HO2 uptake. Potential HO2 loss processes and their atmospheric contributions are discussed.